Chapter 22 - Magnetism - Problems and Conceptual Exercises - Page 792: 10

$1.38\times 10^6\frac{m}{s^2}$

We know that $a=\frac{evBsin90^{\circ}}{m}$ We plug in the known values to obtain: $a=\frac{1.6\times 10^{-19}(355)(4.05\times 10^{-5})}{1.673\times 10^{-27}}$ $a=1.38\times 10^6\frac{m}{s^2}$